JUCHITÁN DE ZARAGOZA, Mexico — Under the glare of portable floodlights and the flashlights that some held, men in sweat-soaked jumpsuits dug into a hillock of rubble in this town, the night after the largest earthquake to hit Mexico in a century flattened buildings here and across southern Mexico.

Atop the mound of debris, the men at times moved like archaeologists, sifting with bare, dirt-encrusted hands, chunk by concrete chunk. At other times, they powered up an excavator, which, with its own brutish precision, moved the workers closer to their goal.

There was a man under there — perhaps alive, perhaps dead.

Throughout Friday, victims were pulled from the ruins of homes, shops and offices in Juchitán de Zaragoza, a town of 100,000 in Oaxaca State: at least 36 dead, more than 300 injured.

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Residents of Juchitán de Zaragoza, Mexico, waited for news about a police officer buried under the rubble of a collapsed building.CreditBrett Gundlock for The New York Times

The earthquake, which was felt as far north as Mexico City, more than 300 miles away, had killed at least 61 people across southern Mexico as of Saturday morning. But no place had lost more than Juchitán.

President Enrique Peña Nieto, seeking to soothe the nation, visited the town on Friday afternoon.

“Indeed, the strength of this earthquake was devastating, but we are also certain that the strength of unity, the strength of solidarity and the strength of shared responsibility will be greater,” Mr. Peña Nieto said in a statement. By nightfall, he and his entourage were gone.

The earthquake that struck was more powerful than the one in 1985 that killed about 10,000 people, many in Mexico City. Thursday’s quake, however, was farther away from Mexico City and more directly affected a far less populated region of Mexico, leading to a significantly lower casualty total.

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Rescue workers searched for Juan Jiménez, the police officer buried in the rubble of the city hall building, where he was on duty when the earthquake struck on Thursday.CreditBrett Gundlock for The New York Times

But nearly a full day later, there was one last person to try to save in town.

The rubble the rescue workers were digging through had once been the town hall, and trapped inside was a 36-year-old police officer, Juan Jiménez, who for 18 years had stood guard there.

He was now buried under a story of wreckage, on the ground where he last stood. Finding him would allow the town to move from the rescue phase to repair and recovery. The search for him would continue until close to midnight on Friday, then resume at dawn on Saturday.

“This becomes part of our history,” said Scherezada Gómez, 45, a high school teacher who was among about 150 residents who clustered behind yellow police tape late Friday, watching the painstaking search unfold. “With a lot of faith we will overcome this.”

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Members of Mexico’s military paused for a rest during the rescue operation at the city hall in Juchitán de Zaragoza.CreditBrett Gundlock for The New York Times

The night was hot and humid in the town, much of which was still without electricity or running water.

Many residents, anxious about aftershocks and the possibility of another quake, hauled cushions and mattresses out of their damaged homes and settled down for the night under the open sky, on sidewalks and playgrounds, in parks and front patios. Many stayed close to their homes, vigilant for looters.

Oscar Cruz and his wife, Noemí Jiménez, and their three children, had found a place to rest in a parking lot. Growing up in Mexico, they had become accustomed to earthquakes. But Thursday night’s episode, they said, was like nothing they had ever experienced.

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Family members held a wake for Angelina Domínguez Díaz, 69, a victim of the earthquake in Juchitán de Zaragoza.CreditBrett Gundlock for The New York Times

“It was like we were thrown into a blender and someone pushed the Level 5 button,” Ms. Jiménez recalled.

The family’s house was destroyed, and they estimated that it would take two years to rebuild.

“It’s going to be very difficult to recover from this, and it’s going to take a long time,” Mr. Cruz said. “Little by little.”

Late into the night, the team of rescuers — marines, federal police officers and disaster specialists — kept digging, their dark jumpsuits stained gray with pulverized concrete.

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Members of a family in Juchitán de Zaragoza slept outside after their home was destroyed by the earthquake.CreditBrett Gundlock for The New York Times

Among the crowd that observed the operation were the wife and three sons of the missing man. They stood in a cocoon of relatives. They had been there since 6 a.m.

The residents watched in a kind of silent vigil. Quiet was essential: The rescuers trained their ears for any sign of life in the wreckage.

“We are desperate,” whispered Rosa Jiménez, the missing police officer’s sister. “Please get him out of there. We’re waiting for a miracle. I ask God to do this miracle for us, that he live.”

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Victor Sánchez, a resident of Juchitán de Zaragoza, looked through the remains of his home after the earthquake.CreditBrett Gundlock for The New York Times

At one point a searcher leaned close to the rubble and yelled: “Is anyone alive? Please make a sound. We’re coming for you, we’re coming for you.”

There was no response.

At times one of them would disappear into a hole in the pile — first his head, then his body — emerging a short time later with nothing new to report.

On Friday night, a member of the search team pulled a black T-shirt from the rubble. The searcher carried it over to Mr. Jiménez’s sons.

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Irma López Sánchez, center, was comforted by relatives after the body of her husband, Juan Jiménez, was found Saturday in the ruins of the city hall building in Juchitán de Zaragoza.CreditBrett Gundlock for The New York Times

“Is this your dad’s shirt?” he asked. Yes, they said, and the searcher handed it to them.

Later, someone pulled a black baseball cap from the debris and took it over to the sons. They said they recognized that, too.

The supervisor of the national police unit involved in the search, Israel Ponce, put the cap on the head of the youngest of the sons, Wilhem, 12. Mr. Ponce was trying to be cheerful, to buoy the boys’ spirits. “You look really handsome with that hat,” he said.

Wilhem forced a smile; he was trying to play along and was struggling. He looked up at Mr. Ponce. He had a question.

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Many houses and other buildings were destroyed by the earthquake in Juchitán de Zaragoza.CreditBrett Gundlock for The New York Times

“But can you tell me if my dad’s O.K.?”

Mr. Ponce was noncommittal, promising only that his team would continue to look for the boy’s father.

Wilhem’s question was answered Saturday afternoon.

Hundreds of residents had gathered over the course of the morning to watch the rescue operation, though Mr. Jiménez’s two youngest sons, including Wilhem, had stayed home with their mother after spending Friday at the search site.

Suddenly, the missing officer’s relatives received word that Mr. Jiménez had been found. A group of them rushed forward but were stopped by police officers.

Mr. Jiménez was dead. The town’s death toll had climbed to 37, and the national death toll to 62.

As rescuers pulled Mr. Jiménez’s body from the rubble, three of his relatives collapsed to the ground, sobbing in anguish, and his eldest son, Victor Manuel, 14, rushed the police cordon but was restrained.

The rescuers wrapped the body in a cloth, slid it into the back of a police truck and drove it to the coroner’s office.

The relatives remained for a few minutes, hugging one another, as residents — many of them crying, too – surrounded them. Then they started walking toward the Jiménez house, to break the news to the officer’s wife and two youngest sons.

Paulina Villegas reported from Juchitán de Zaragoza, and Kirk Semple from Mexico City.

A version of this article appears in print on , on Page A8 of the New York edition with the headline: Mexican Earthquake Leaves A Town Digging for Survivors. Order Reprints | Today’s Paper | Subscribe